Power tool and method of assembling parts using a two-part separable washer

ABSTRACT

A washer has a body having an axis and provided with a first bearing face surface located at one axial side and adapted to cooperate with a nut, a second bearing face surface located at an opposite axial side and adapted to cooperate with an object, at least one third turning resistant surface adapted to cooperate with a thread of the bolt, the body having at least one resistive point arranged so that when the nut is turned and turns the bolt the body of the washer stops the bolt from turning and thereby the nut creates a pull on the bolt which elongates the bolt in an axial direction and applies to the body of the washer an axial force which overcomes the at least one resistive point so that a portion of the body of the washer is allowed to be pulled axially when the bolt elongates. Also, a fastener with the washer is provided, as well as a method of and a tool for fastening objects with the use of the washer.

CROSS-REFERENCE TO A RELATED APPLICATION

This application is a divisional of U.S. patent application Ser. No. 10/691,831, filed Oct. 23, 2003, which is a continuation-in-part of Ser. No. 10/427,103, filed Apr. 30, 2003, now U.S. Pat. No. 6,929,439, which is a divisional of Ser. No. 10/010,377, filed Dec. 6, 2001, now U.S. Pat. No. 6,609,868. Ser. No. 10/691,831 is also a continuation-in-part of Ser. No. 10/120,343, filed Apr. 11, 2002, now U.S. Pat. No. 6,883,401, and a continuation-in-part of Ser. No. 10/112,101, filed Mar. 29, 2002.

BACKGROUND OF THE INVENTION

The present invention relates to a washer, a fastener provided with a washer, and a method of and a power tool for fastening objects.

It is known to fasten objects with one another with power tools which use fasteners having a multi-part replacement nut, for example including an inner sleeve, an outer sleeve, and a washer. Such a replacement nut is disclosed for example in our U.S. Pat. No. 5,341,560. Another replacement nut is disclosed in our U.S. Pat. No. 6,254,323 in which a bolt has a spline underneath its upper thread, to which a washer is non-rotatably connected, and the bolt also has engaging means for applying a reaction force, while an active force of the same tool turns the nut on the bolt thread and the washer face. In the fastener disclosed in both above mentioned patents, the common features are the use of the action and reaction force of one tool, the elimination of reaction arms on power tools, the conversion of torque to torsion-free bolt stretching and obtaining for the first time the desired residual bolt load rather than a torque, which is estimated based on calculated frictions rather than on actual frictions or a tension, which is based on estimated bolt relaxation when the force is transmitted from the elongated bolt to the hand-tight nut.

Some solutions are disclosed in my patent application Ser. Nos. 10/010,377; 10/112,101, 10/120,343 and 10/427,103.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide a washer, a fastener provided with a washer, a method of and a power tool for fastening with the use of the washer, which provide further solutions to the above specified problems.

In keeping with these objects and with others which will become apparent hereinafter, one feature of the present invention resides, briefly stated, in a washer which has a body having an axis and provided with a first bearing face surface located at one axial side and adapted to cooperate with a nut, a second bearing face surface located at an opposite axial side and adapted to cooperate with an object, at least one third turning resistant surface adapted to cooperate with a thread of the bolt, wherein said body also has at least one resistive point arranged so that when the nut is turned and turns the bolt said body of the washer stops the bolt from turning and thereby the nut creates a pull on the bolt which elongates the bolt in an axial direction and applies to said body of the washer an axial force which overcomes the at least one resistive point so that a portion of said body of the washer is allowed to be pulled axially when the bolt elongates.

Another feature of the present invention resides in a threaded fastener for connecting two parts which constitute an object, which fastener has a bolt having a thread, a nut screwable on the bolt, and a washer to be applied between the nut and the object and including a body having an axis and provided with a first bearing face surface located at one axial side and adapted to cooperate with a nut, a second bearing face surface located at an opposite axial side and adapted to cooperate with an object, at least one third turning resistant surface adapted to cooperate with a thread of the bolt, wherein the body also has at least one resistive point arranged so that when the nut is turned and turns the bolt said body of the washer stops the bolt from turning and thereby the nut creates a pull on the bolt which elongates the bolt in an axial direction and applies to said body of the washer an axial force which overcomes the at least one resistive point so that a portion of said body of the washer is allowed to be pulled axially when the bolt elongates.

Still another feature of the present invention resides in a method of assembly at least two parts of an object with one another, comprising the steps of introducing a bolt having a thread into the parts so that a free end of the bolt extends outwardly beyond at least one side of the parts; placing a washer on said free end of said bolt; threadably connecting a nut to said free end of said bolt so as to abut against the washer; placing a power tool so as to turn the nut with a turning portion of the power tool connected to the nut to tighten or loosen the bolt, and applying a reaction portion of the power tool to the washer to absorb a reaction force; and providing the body of the washer with a resistive point arranged so that when the nut is turned and turns the bolt said body of the washer stops the bolt from turning and thereby the nut creates a pull on the bolt which elongates the bolt in an axial direction and applies to said body of the washer an axial force which overcomes the at least one resistive point so that a portion of said body of the washer is allowed to be pulled axially when the bolt elongates.

In accordance with still a further feature of the present invention, a power tool for fastening parts forming an object is proposed, which has a housing provided with a non-rotatable element; a power drive in said housing driving a rotatable driving element; a fastener part including a bolt having a thread and an axis and introducible into the parts forming the object, a nut screwable on said bolt and cooperating with said driving element, and a washer to be applied between said nut and the object and cooperating with said non-rotatable element, said washer having an axis and being provided with a first bearing face surface located at one axial side and adapted to cooperate with said nut, a second bearing face surface located at an opposite axial side and adapted to cooperate with the object, and at least one turning resistant surface adapted to cooperate with said thread of said bolt, so that when said nut is turned by said driving element and turns said bolt, said body of said washer stops said bolt from turning and thereby said nut creates a pull on said bolt which elongates said bolt in an axial direction and applies to said body of said washer an axial force which overcomes the at least one resistive point so that a portion of said body of said washer is allowed to be pulled axially when said bolt elongates.

In accordance with one embodiment of the present invention, the washer body can be composed of two parts arranged so that one part prevents initially an axial displacement of the other part which is engaged with the bolt, and thereafter the one part is broken in the region of the resistive point under the action of the axial force applied in response to the elongation of the bolt.

In accordance with another feature of the present invention, the washer body can be formed as a one-piece integral element, which subsequently is broken at the resistive point when the axial force is applied to the washer by the elongating bolt.

In accordance with still another feature of the present invention, the washer body can be formed of two parts, wherein one of the parts is provided with a deformable formation, for example a skirt, a knurl and the like formed so that under the action of the axial force applied in response to the elongation of the bolt, the formation is deformed to allow an axial movement of the parts relative to one another without their turning relative to one another.

In accordance with still a further feature of the present invention, the body of the washer can be composed of two parts which are press-fit in one another, so as to prevent a turning relative to one another but to allow an axial movement relative to one another under the action of the axial force applied in response to the elongation of the bolt.

The novel features which are considered as characteristic for the present invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view showing a washer in accordance with the present invention;

FIG. 2 is a view showing a fastener with a washer and a tool applied to the fastener, and illustrating a fastening method in accordance with the present invention;

FIG. 3 is a view showing a further embodiment of the washer in accordance with the present invention;

FIG. 4 shows still a further embodiment of the washer in accordance with the present invention;

FIG. 5 shows an additional embodiment of the washer in accordance with the present invention; and

FIG. 6 shows still a further embodiment of the washer in accordance with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows a washer in accordance with the present invention, which is identified with reference numeral 1 as a whole. The washer 1 has a body which is identified with reference numeral 2. The body 2 of the washer 1 has a first upper bearing face surface 3 adapted to cooperate with a nut, a second lower bearing face surface 4 adapted to cooperate with an object which can be formed as two parts to be assembled with one another, and at least one turning resistant surface identified with reference numeral 5.

The first and second bearing face surfaces 3 and 4 are spaced from one another in an axial direction or in other words in a direction of an axis A1. The at least one third turning resistant surface 5 is located radially inwardly of the body 2 of the washer 1. The third turning resistant surface 5 is formed so as to engage with or wedge in a thread of the bolt, for example by providing a corresponding thread 6 on the turning resistant surface 5.

As can be seen from FIG. 1, the body 2 of the washer 1 is composed of two parts 7 and 8 located substantially radially adjacent to one another, so that the part 7 is located radially inwardly of the part 8. The turning resistant surface 5 with the thread 6 is provided radially inwardly on the part 7. The part 8 has a projection 9 which is located above the part 7 and prevents an axial upward displacement of the part 7. The projection 9 of the part 8 forms a resistive point, which in this embodiment is formed as a breaking point. In particular, the projection 9 is designed so that it can break under the action of a certain force acting in an axial upward direction.

FIG. 2 shows a fastener provided with the washer, and with a tool applied to the fastener. The fastener has a nut 10 having an inner thread 11. The fastener further has a bolt 12 provided with an outer thread 13, and having an axis A2. The nut 10 has a lower bearing face surface 14 which is adapted to be placed on the upper bearing face surface 3 of the body 2 of the washer 1. The outer thread 13 of the bolt 12 engages with the inner thread 11 of the nut 10, and also engages with an inner thread 6 of the body 2 of the washer 1.

A power tool in accordance with the present invention is shown in FIG. 2 and identified with reference numeral 15. The power tool has a housing which is identified with reference numeral 20 and a power drive which is identified with reference numeral 21. The power drive is formed for example as a cylinder-piston unit which includes a cylinder 24 and a piston 25 which is movable in the cylinder and provided with a piston rod 26. The reciprocating movement of the piston rod 26 with the piston 25 is converted into a rotary movement of a ratchet 28 through at least one drive plate 27 provided with a not shown pawl engageable with teeth of the ratchet 28. A driving element 16 is connected with the turnable ratchet 28 on the one hand and engages the nut 10 on the other hand. In order to provide such an engagement the inner surface of the driving element 16 can be provided with connecting means, for example formed as a polygonal inner surface, etc. A non-rotatable element 17 is connected to the immovable housing 20 to absorb a reaction created during turning of the driving element. The non-rotatable element 17 engages the body 2 of the washer 1 to prevent its rotation about the axes A1 and A2 which coincide with one another when the fastener is assembled. In order to engage the washer, the non-rotatable element 17 is provided with connecting means formed for example as a polygonal inner surface, etc.

The fastener with the washer is provided for fastening an object which is identified with reference numeral 18, in particular, to assemble parts 19 and 19′ of the object 18 with one another.

When as shown in FIG. 2, the power tool 15 is placed on the fastener so as to tighten or loosen the nut, the turning element 16 which is connected to the nut 10 turns the nut to overcome a thread friction with the bolt 12 and the facial friction with the washer 1 so as to turn the nut, and the non-rotatable element 17 holds the washer 1 to absorb the reaction force due to the facial friction of the washer 1 with the nut 10, its facial friction with one side of the part 19′, and its turning friction with the bolt 12, so that the washer 1 does not turn but absorbs the reaction force of the power tool. Initially, when the nut 10 rotates, the bolt 12 rotates together with the nut; however, the stationary washer 1 wedges the stationary part 7 into the bolt thread 13, so that the bolt stops turning because of the interengagement of its outer thread 13 with the thread 6 of the washer 1. Therefore, the bolt 12 is stopped, and an axial force is applied to the washer 1, in particular to its part 7 in an axial upward direction when the bolt 12 is elongated by the turning nut 10. Under the action of this axial upward force, the resistive point of the washer is overcome and in particular the projection 9 of the part 8 of the washer 1 breaks off and the part 8 of the washer 1 is pulled upwardly.

FIG. 3 shows another embodiment of the washer in accordance with the present invention. Here the washer which is identified with reference numeral 1′ has a body 2′ which is formed as a one-piece integral element with a partition 31 and a groove 32 provided to reduce a thickness of the partition and to make it breakable.

The operation of the washer 1′ in accordance with the second embodiment of the present invention is substantially similar to the operation of the washer 1 of the embodiment shown in FIG. 1. When the nut 10 is turned by the driving element 16 of the power tool, the bolt 12 has a tendency to turn together with the nut. As the washer 1′ is held stationary and consequently the inner part 7′, the bolt becomes stationary due to the interengagement of its outer thread 13 with the inner thread 6′ of the body 2′ of the washer 1, but is elongated in the axial direction. An axial force which is generated during the elongation of the bolt 12 is applied axially upwardly to the radially inner part 7′ of the washer 1′, trying to displace the inner part 7′, so that eventually it breaks the partition 31, which constitutes the resistive point, and displaces the inner part 7′ of the washer 1′ axially upwardly relative to the outer part 8′.

FIG. 4 shows a further embodiment of the washer in accordance with the present invention. Here the washer which is identified with reference numeral 1″ has a body 2″. The body 2″ of the washer 1″ has a first upper bearing face surface 3″ adapted to cooperate with the nut, a second lower bearing face surface 4″ adapted to cooperate with an object, and at least one turning resistant surface identifies with reference numeral 5″. The at least one third turning resistant surface 5″ is located radially inwardly and is formed to engage as a wedge in a thread of the bolt, for example by providing a corresponding thread 6″ on the turning resistant surface 5″. The body 2″ of the washer 1″ is composed of two parts 7″ and 8″ located substantially radially adjacent to one another, so that the part 7″ is located radially inwardly of the part 8″. The turning resistant surface 5″ with the thread 6″ is provided radially inwardly on the part 7″.

The part 7″ has a skirt-shaped portion 33 which is received in a correspondingly shaped lower portion 34 of an opening of the part 8″. The formations 33, 34 form a resistive point of the washer. When the part 7″ is pulled up after stopping the bolt from turning, the skirt-shaped portion 33 of the part 7″ is slightly and permanently deformed to the size of to the straight portion of the inner opening of the part 8″, to permit further upward sliding of the part 7″ as the bolt elongates.

FIG. 5 is a view showing a further embodiment of the present invention. The washer is identified with reference numeral 1′″ and has a body 2′″. The body 2′″ of the washer 1′″ has a first upper bearing surface 3′″ adapted to cooperate with the nut, a second lower bearing face surface 4′″ adapted to cooperate with an object, and at least one turning resistant surface identifies with reference numeral 5′″. The at least one third turning resistant surface 5′″ is located radially inwardly and is formed to engage as a wedge in a thread of the bolt, for example by providing a corresponding thread 6′″ on the turning resistant surface 5′″. The body 2′″ of the washer 1′″ is composed of two parts 7′″ and 8′″ located substantially radially adjacent to one another, so that the part 7′″ is located radially inwardly of the part 8′″. The turning resistant surface 5′″ with the thread 6′″ is provided radially inwardly on the part 7′″.

In the embodiment shown in FIG. 5 the part 7′″ is provided in its lower portion with an outer knurl-portion 35 which is received in a correspondingly shaped lower portion 36 of an opening of the part 8″. The knurl-shaped portion 35 of the part 7′″ is press-fit in the lower portion 36 of the opening in the part 8′″. During the operation when the bolt is stopped and elongates, the knurl-shaped portion 35 is squashed, but still leaves enough friction to permit an upward movement of the part 7′″ relative to the part 8′″ without turning.

In the embodiment shown in FIG. 6 the washer is identified with reference numeral 1″″ and has a body identified as 2″″. The body 2″″ of the washer 1″″ has a first upper bearing face surface 3″″ adapted to cooperate with the nut, a second lower bearing face surface 4″″ adapted to cooperate with an object, and at least one turning resistant surface identifies with reference numeral 5″″. The at least one third turning resistant surface 5″″ is located radially inwardly and is formed to engage as a wedge in a thread of the bolt, for example by providing a corresponding thread 6″″ on the turning resistant surface 5″″. The body 2″″ of the washer 1″″ is composed of two parts 7″″ and 8″″ located substantially radially adjacent to one another, so that the part 7″″ is located radially inwardly of the part 8″″. The turning resistant surface 5″″ with the thread 6″″ is provided radially inwardly on the part 7″″.

In the embodiment of FIG. 6 the diameter of an outer surface 37 of the part 7″″ and the diameter of an inner surface 38 of an opening in the part 8″″ are selected so that the inner surface 38 of the opening of the part 8″″ is press-fit on the outer surface 37 of the part 7″″. The surfaces 37 and 38 form a resistive point of the washer. The press-fit is selected so that after the bolt is stopped and an axial force is applied to the washer 1″″ in an axial direction when the bolt 12 is elongated, the press fit of the surfaces 37 and 38 is overcome and the part 7″″ can axially slide relative to the part 8″″.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the types described above.

While the invention has been illustrated and described as embodied in washer, fastener provided with a washer, method of power tool for fastening with the use of the washer, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims. 

1. A method of assembly of at least two parts of an object with one another, comprising the steps of introducing a bolt having a thread into the parts so that a free end of the bolt extends outwardly beyond at least one side of the parts; placing a washer on the free end of the bolt; threadingly connecting a nut to the free end of the bolt so as to abut against the washer; placing a power tool so as to turn the nut with a rotatable element of the power tool connected to the nut to tighten or loosen the bolt and applying a non-rotatable element of the power tool to the washer to absorb a reaction force; and providing the body of the washer with a radially outer part having a first bearing face surface located at one axial side and adapted to cooperate with the nut and a second bearing face located at an opposite axial side and adapted to cooperate with the object, a radially inner part having at least one turning resistance surface, and a resistive point arranged so that when the nut is turned and turns the bolt said body of the washer stops the bolt from turning and thereby the nut creates a pull on the bolt which elongates the bolt in an axial direction and applies to said turning resistant surface an axial force which overcomes the at least one resistive points so that said radially outer part of said body does not move axially, while said radially inner part of said body of the washer with said turning resistant surface cooperating with the thread of the bolt is allowed to be pulled axially when the bolt elongates; and providing in said radial outer part an axial space, into which said radially inner part moves as it is pulled axially when the bolt elongates.
 2. A power tool in combination with a fastener for fastening an object, comprising a housing provided with a non-rotatable element; a power drive in said housing for driving a rotatable driving element; a fastener part including a bolt having a thread and an axis and introducible into parts forming the object, a nut screwable on said bolt and cooperating with said driving element of said power drive, and a washer to be applied between said nut and the object and cooperating with said non-rotatable element of said housing, said washer having a body with an axis and being provided with a radially outer part having a first bearing face surface located at one axial side and adapted to cooperate with said nut and a second bearing face located at an opposite axial side and adapted to cooperate with the object, a radially inner part having at least one turning resistant surface adapted to cooperate with said thread of said bolt, and at least one resistive point, so that when said nut is turned by said driving element and turns said bolt, said body of said washer is held by said non-rotatable element and stops said bolt from turning and thereby said nut creates a pull on said bolt which elongates said bolt in an axial direction and applies to said turning resistant surface an axial force which overcomes the at least one resistive point so that said radially outer part of said body does not move axially, while said radially inner part of said body of the washer with said turning resistant surface cooperating with the thread of the bolt is allowed to be pulled axially when said bolt elongates; and said radially outer part and said radially inner part being configured so that an axial space remains in said radially outer part, into which said radially inner part moves as it is pulled axially when the bolt elongates. 